A wide variety of tillage implements are used to prepare soil for planting. Some such implements include two or more sections articulated to one another so as to perform multiple functions as they are pulled through fields by a single tractor or other prime mover. One such implement is a cultivator/harrow, which is capable of simultaneously tilling soil and leveling the tilled soil in preparation for planting. This implement includes a cultivator that is towed by a tractor or other prime mover, and a unitary or sectional tine harrow that is towed by the cultivator.
The cultivator includes a plurality of cultivator members or “sweeps” (sometimes known as shanks or chisel plows) that are suspended from a frame and that rip into the soil as the machine is pulled across the ground to till the soil. The sweeps are arranged in transversely extending rows. The sweeps of each row are transversely staggered relative to the sweeps of the adjacent rows. In use, each successive row of sweeps tills part of a strip of soil left untilled by the preceding row. The last row of sweeps tills the last untilled strip of the swath, leaving ridges between the sweeps that are flanked by valleys directly behind the sweeps.
The harrow is designed to level the tilled soil sufficiently to produce a seedbed that is as level as possible and that is relatively clod free. A clod free, level seedbed formed from soil of relatively small particle size is desirable because it facilitates planting to a uniform depth and, accordingly, promotes uniform germination and uniform emergence. The typical harrow includes a plurality of grounded-engaging tines that penetrate the soil tilled by the cultivator. Multiple harrow sections are often provided, each of which spans a proportionate part of the transverse width of the swath tilled by cultivator. The tines are typically arranged in longitudinally extending, transversely spaced rows. They are intended to redirect soil from ridges or windrows left by the cultivator sweeps into the adjacent valleys, hence leveling the tilled surface. The tines, and/or related equipment such as rotating baskets, also firm the soil and break up clods.
Many harrows and harrow sections are designed for use strictly as an attachment to a cultivator. The tines in adjacent rows typically are indexed relative to one another to provide nearly complete coverage of the swath tilled by the cultivator. However, the tines are not indexed with respect to the cultivator sweeps. As a result, some of the tines of the typical harrow are not properly positioned to engage the ridges left by the cultivator sweeps in an optimal sequence. Harrows of this type, therefore, do not level the ridges left by the cultivator sweeps as well as may be desired. In fact, some of the harrow tines may be positioned so as to direct soil towards the ridges left by the cultivator sweeps rather than away from them, hence defeating the purpose of the harrow.
These problems are compounded by modern agricultural machinery, which operates at travel speeds of up to 9 mph. A cultivator operating at these speeds leaves deeper ridges than earlier cultivators operated at lower speeds. Known tine placement configurations, even if properly indexed relative to one another produce uniform ridges, still produce ridges that are too large to permit planting as the next operation.
Some of the problems mentioned above can be alleviated by replacing the last row(s) of tines with rotary wheels or crumbler wheels that are designed to roll behind the rows of tines and flatten the ridges left by the tines. However, current wheels are not sufficiently even or level relative to the seedbed left by the tines to adequately perform these functions, nor do they reduce soil clod size sufficiently.
The need therefore has arisen to provide a tine harrow that is configured to be towed by a cultivator and that has tines that are properly indexed, both relative to one another and to the cultivator sweeps, to maximize the leveling capability of the harrow.